B.A.J.M. de Mol

Retrograde aortic and selective organ perfusion during thoracoabdominal aortic aneurysm repair

OBJECTIVES To evaluate the possible prevention of renal and intestinal ischaemia during surgery of thoracoabdominal aortic aneurysms (TAAA) by use of retrograde and selective organ perfusion. DESIGN Prospective study. MATERIALS Thirty-three consecutive patients underwent TAAA repair, six of whom had a previous type B dissection: 14 patients (35%) had type I TAAA, 12 patients type II (32%), three patients type III (15%) and four patients type IV (18%). Mean age was 61 years (range 22-84 years). METHODS In patients with type I TAAA, retrograde aortic perfusion was performed by means of a left atrium femoral artery bypass or partial cardiopulmonary bypass. In type II, III and IV the same procedure was performed; however, following cross-clamping and opening of the abdominal aorta, the coeliac trunc, superior mesenteric and both renal arteries were selectively perfused with four Pruitt-catheters (9 Fr.), connected as an octopus to the extracorporal circulation. RESULTS All patients survived the surgical procedure. The minimal volume flow through each octopus catheter was 60 ml/min. Urine output was uninterrupted in all patients, irrespective of the aortic cross-clamp time. Only one patient (3%), who already had renal insufficiency, developed renal failure. Total in-hospital mortality was 15%, paraplegia occurred in 12%. CONCLUSION Retrograde aortic and selective organ perfusion is a safe technique and can prevent ischaemic renal and intestinal damage during cross-clamping of the aorta in thoracoabdominal aneurysm surgery.

Sarcopenic obesity is associated with adverse clinical outcome after cardiac surgery.

BACKGROUND & AIMS Both undernutrition - low fat free mass (FFM) - and obesity - high fat mass (FM) - have been associated with adverse outcome in cardiac surgical patients. However, whether there is an additional effect on outcome of these risk factors present at the same time, that is sarcopenic obesity (SO), is unknown. Furthermore, the association between SO and muscle function is unidentified. METHODS AND RESULTS In 325 cardiac surgical patients, we prospectively analysed the association between preoperative FFM and FM, measured by bioelectrical impedance spectroscopy, and postoperative adverse outcomes, and their correlation with muscle function - handgrip strength (HGS). SO was associated with postoperative infections (28.2% vs. 5.3%, adj. odds ratio (OR): 7.9; 95% confidence interval (CI): 1.2-54.1; p=0.04). Further, a low FFM index (FFMI; kgm(-2)) was associated with postoperative infections (18.5% vs. 4.7%, adj. OR: 6.6; 95% CI: 1.7-25.2; p=0.01) while a high FM index (FMI; kgm(-2)) was not. Both components of SO, FFMI and FMI, correlated with HGS (FFMI: r=0.570; p<0.001, FMI: r=-0.263; p<0.001). CONCLUSION SO is associated with an increased occurrence of adverse outcome after cardiac surgery. Our results suggest an additional risk of a low FFMI and high FMI present at the same time. Furthermore, SO is characterised by less muscle function. We advocate determining body composition in cardiac surgical patients to classify and treat undernourished patients, in particular those who are also obese.

The influence of regional spinal cord hypothermia on transcranial myogenic motor-evoked potential monitoring and the efficacy of spinal cord ischemia detection

OBJECTIVE Myogenic motor-evoked responses to transcranial electrical stimulation (transcranial myogenic motor-evoked potentials) can rapidly detect spinal cord ischemia during thoracoabdominal aortic aneurysm repair. Recent evidence suggests that regional spinal cord hypothermia increases spinal cord ischemia tolerance. We investigated the influence of subdural infusion cooling on transcranial myogenic motor-evoked potential characteristics and the time to detect spinal cord ischemia in 6 pigs. METHODS Regional hypothermia was produced by subdural perfusion cooling. A laminectomy and incision of the dura were performed at L2 to advance 2 inflow catheters at L4 and L6, to cool the lumbar subdural space with saline solution. Two temperature probes were advanced at L3 and L5, and 1 cerebrospinal fluid pressure line was advanced at L4. Spontaneous cerebrospinal fluid outflow was allowed. Spinal cord ischemia was produced by clamping a set of critical lumbar arteries, previously identified by transcranial myogenic motor-evoked potentials and lumbar artery clamping. The time between the onset of ischemia and detection with transcranial myogenic motor-evoked potentials (amplitude < 25%) was determined at cerebrospinal fluid temperatures of 37 degrees C and 28 degrees C. Thereafter, the influence of progressive cerebrospinal fluid cooling on transcranial myogenic motor-evoked potential amplitude and latency was determined. RESULTS The time necessary to produce ischemic transcranial myogenic motor-evoked potentials, after the clamping of critical lumbar arteries, was not affected at moderate subdural hypothermia (3.8 +/- 0.9 min) compared with subdural normothermia (3.2 +/- 0.5 min; P =.6). Thereafter, progressive cooling resulted in a transcranial myogenic motor-evoked potential amplitude increase at 28 degrees C to 30 degrees C and was followed by a progressive decrease. Response amplitudes decreased below 25% at 14.0 degrees C +/- 1.1 degrees C. The influence of cerebrospinal fluid temperature on transcranial myogenic motor-evoked potential amplitude was best represented by a quadratic regression curve with a maximum at 29.6 degrees C. In contrast, transcranial myogenic motor-evoked potential latencies increased linearly with decreasing subdural temperatures. CONCLUSIONS Detection of spinal cord ischemia with transcranial myogenic motor-evoked potentials is not delayed at moderate subdural hypothermia in pigs. At a cerebrospinal fluid temperature of 28 degrees C, transcranial myogenic motor-evoked potential amplitudes are increased. Further cerebrospinal fluid temperature decreases result in progressive amplitude decreases and latency increases.

Perioperative hyperinsulinaemic normoglycaemic clamp causes hypolipidaemia after coronary artery surgery

BACKGROUND Glucose-insulin-potassium (GIK) administration is advocated on the premise of preventing hyperglycaemia and hyperlipidaemia during reperfusion after cardiac interventions. Current research has focused on hyperglycaemia, largely ignoring lipids, or other substrates. The present study examines lipids and other substrates during and after on-pump coronary artery bypass grafting and how they are affected by a hyperinsulinaemic normoglycaemic clamp. METHODS Forty-four patients were randomized to a control group (n=21) or to a GIK group (n=23) receiving a hyperinsulinaemic normoglycaemic clamp during 26 h. Plasma levels of free fatty acid (FFA), total and lipoprotein (VLDL, HDL, and LDL)-triglycerides (TG), ketone bodies, and lactate were determined. RESULTS In the control group, mean FFA peaked at 0.76 (sem 0.05) mmol litre(-1) at early reperfusion and decreased to 0.3-0.5 mmol litre(-1) during the remaining part of the study. GIK decreased FFA levels to 0.38 (0.05) mmol litre(-1) at early reperfusion, and to low concentrations of 0.10 (0.01) mmol litre(-1) during the hyperinsulinaemic clamp. GIK reduced the area under the curve (AUC) for FFA by 75% and for TG by 53%. The reduction in total TG was reflected by a reduction in the VLDL (-54% AUC) and HDL (-42% AUC) fraction, but not in the LDL fraction. GIK prevented the increase in ketone bodies after reperfusion (-44 to -47% AUC), but was without effect on lactate levels. CONCLUSIONS Mild hyperlipidaemia was only observed during early reperfusion (before heparin reversal) and the hyperinsulinaemic normoglycaemic clamp actually resulted in hypolipidaemia during the largest part of reperfusion after cardiac surgery.

Mechanical manipulator for intuitive control of endoscopic instruments with seven degrees of freedom

Performing complex tasks such as vascular anastomosis in minimally invasive surgery (MIS) is demanding due to a disturbed hand-eye co-ordination, the application of non-ergonomic instruments with limited number of degrees of freedom (DOFs) and a lack of three-dimensional perception. Robotic tele-manipulatory systems enhance surgical dexterity by providing up to seven DOFs. They allow the surgeon to operate in an ergonomically favourable position with more intuitive manipulation of the instruments. Robotic systems, however, are very bulky, expensive and do not provide any force feedback from the tissue. The aim of our study is to develop a simple mechanical manipulator for MIS. The Minimally Invasive Manipulator (MIM) is a purely mechanical device. When manipulating the handle of the MIM, the surgeons wrist and grasping movements, which are essential for suturing, are directly transmitted to the deflectable instrument tip in seven DOFs. It gives the surgeon direct control of the instrument tip. First phantom experience indicates that the system functions properly. The MIM provides force feedback to improve safety. A set of MIMs seems to be an economical and compact alternative to robotic systems and will offer more surgeons the capability to perform complex MIS and to shorten their learning curve.

Towards minimally invasiveness: transcatheter aortic valve implantation under local analgesia exclusively

Background: Both, general anaesthesia (GA) and local analgesia (LA) with or without sedation are options for periprocedural anaesthetic management of transfemoral transcatheter aortic valve implantation (TAVI). We report the safety and feasibility of TAVI under LA and provide our own experience in the largest cohort so far reported. Methods: A total of 178 consecutive patients planned for transfemoral TAVI were included in this study. Patients were treated with the Medtronic Core Valve (n=77) or the Edwards Sapien (n=101) at operators’ discretion. Periprocedural anaesthetic management, procedural characteristics, and outcomes were assessed. Results: Of the 178 patients (34% male), 4 (2.2%) needed a conversion to general anaesthesia (prosthesis embolism, 2 complicated peripheral vasculature puncture/closures, restlessness). Periprocedural transoesophageal echocardiography was not necessary. Premedication included temazepam, lorazepam, or midazolam in 76% of patients. In total 115 patients (66%) received conscious sedation, 34% received sedative medications. Only nine patients developed a delirium during admission (5%). All-cause 30day-mortality was 9 (5%). NYHAclass decreased significantly from 3±0.6 to 1±0.9 (p=0.04). Conclusion: Transfemoral TAVI using exclusively local analgesia and fluoroscopic guidance is safe and feasible with a very low rate of conversion. The fragile TAVI-population may benefit from this anaesthetic management. 14745_SEberl_BW.indd 30 25-07-17 12:43 31 TRANSCATHETER AORTIC VALVE IMPLANTATION UNDER LOCAL ANALGESIA EXCLUSIVELY 3 Transcatheter Aortic Valve Implantation (TAVI) was started in most centres using general anaesthesia (GA) and the same monitoring standard as for patients scheduled for open surgical aortic valve replacement. After gaining experience, few centres switched to local anaesthesia (LA) with or without sedation. Currently both, GA and LA (with or without sedation) are options for the anaesthetic management of TAVI patients. Whether LA is superior to GA has not been addressed in randomised trials before and no consensus upon the preferable method has been reached yet. We report on safety and feasibility of TAVI under LA and present our own experiences in the largest cohort so far reported. At our institution, transfemoral TAVI procedures started in 2007 under GA (n=55). In an effort to minimise invasiveness in this fragile patient population, LA became the standard method for transfemoral TAVI`s beginning October 2010. We included consecutive patients who were planned for TAVI under LA between October 2010 and May 2013. All patients were rejected for surgical treatment due to anticipated high surgical risk by our heart team. Patients signed written informed consent for the procedure, data collection and utilisation according the ethical guidelines of our institute. All patients received pre-procedural consultation by both, the operator as well as the anaesthesiologist. Premedication and use of conscious sedation were left at the discretion of the cardioanaesthesiologist. A total of 40 cc lidocaine 1% mixed with bupivacaine 0.5% (T 1/2 =2.7h) was injected in the percutaneous femoral access site for local wound analgesia. Appropriate valve positioning was achieved by fluoroscopy and aortography without the use of transoesophageal echocardiography (TOE). Results and complications were assessed based on direct patient contact, haemodynamics, angiography, and transthoracic echocardiography (TTE). A cardiovascular anaesthesiologist was constantly present to monitor the patient, stabilise haemodynamics, or perform GA if necessary. All patients treated under LA were postprocedurally observed on the Cardiac Care Unit (CCU) instead of being transported to the Intensive Care Unit (ICU) as is it standard after GA. For the clinical endpoint definitions the criteria of the Valve Academic Research Consortium were used. A comparison was made between the group of patients treated under LA and conscious sedation and the group under LA without conscious sedation. Differences of continuous variables between two groups were analysed with a two-tailed student’s t-test or Mann– Whitney U test where appropriate. Of the 178 patients included, 4 patients (2.2%) needed a conversion to GA (1 conversion to surgery due to prosthesis embolism, 2 complicated peripheral vasculature puncture/ 14745_SEberl_BW.indd 31 25-07-17 12:43

The quality of Intensive Care nursing before, during, and after the introduction of nurses without ICU-training

OBJECTIVE The forecasted shortage of nurses specialized in intensive care seriously threatens the service level in the intensive care units (ICUs). This problem might partly be solved by introducing nurses without ICU experience who can provide basic nursing care to relieve the workload of the ICU nurses. This prospective controlled study was set up to determine whether such an introduction causes a significant shift in the quality of care. DESIGN A prospective observational study was conducted to measure possible changes in the quality of care by examining the number of predefined nursing errors per patient with an observational instrument, the Critical Nursing Situation Index (CNSI). The CNSI was randomly applied during a preassessment period, an intervention period, and a postassessment period. During the intervention period, 16 full time equivalent nurses were employed with the assignment to assist the ICU nurses with basic care activities for 6 months. SETTING The study was conducted in a 30-bed ICU at the Academic Medical Center in Amsterdam. ANALYSIS The effect of the employment of nurses was expressed as the difference in the incidence of CNSI scores between the preassessment period and the intervention period on the basis of the relative risk ratios. The results of the comparison between the preassessment and the postassessment period were used to express the consistency of the measure. RESULTS The researchers completed 600 CNSI observations in 256 patients in 162 days. Overall incidence rates during the preassessment (13%; 1539/12 222) and postassessment (14%; 1554/11 327) period were comparable, whereas the intervention period showed a diminished overall incidence of 9% (1019/11 395). The overall relative risk (95% CL) was 0.70 (0.56/0.86), indicating a significant risk reduction during the intervention period. CONCLUSION The employment of nurses without ICU training improved the quality of care. This positive effect was primarily explained by the increase in available nursing time.

Topical vascular endothelial growth factor in rabbit tracheal surgery: comparative effect on healing using various reconstruction materials and intraluminal stents

OBJECTIVES The effect of topical vascular endothelial growth factor (VEGF) on post-surgical tracheal healing using various reconstruction materials was studied, with particular regard to prevention of granulation tissue or fibrosis. METHODS Twenty-four New Zealand White rabbits underwent survival surgery using autograft patches (n=6), xenopericardium patches (n=6), intraluminal Palmaz wire stents (n=6), and controls (n=6). Autograft and pericardial half-patches were soaked in topical VEGF (5 microg/ml over 30 min) and saline before reimplantation. Stents and controls received circumferential injections of VEGF and saline in the tracheal wall. At 1-4 months postoperatively, specimens of sacrificed animals were stained with anti-VEGF antibody, followed by morphological and immunohistochemical examination. RESULTS Rabbits with autografts and controls fared well until planned sacrifice. After xenopericardium repair, obstructive intraluminal granulation tissue led to early sacrifice in three rabbits. Stent insertion led to earlier death from airway obstruction in all six rabbits. Topical VEGF reduced granulation tissue after pericardial repair and fibrosis in all repairs except in stents. Remarkably, VEGF-pretreated half-patches and saline half-patches stained similarly high for VEGF, suggesting also local production of VEGF, probably in plasmacells, and in submucosal glands. CONCLUSIONS Autograft repair induces the least granulation tissue and fibrosis, and the best healing pattern. Stents rapidly induced critical airway obstruction, unhindered by VEGF, leading to premature death. Tracheal pretreatment with topical VEGF reduces postoperative fibrosis after autograft and pericardial patch repairs, and reduces granulation tissue after xenopericardium repair. In time, VEGF is probably locally produced, although its potential role in tracheal healing remains to be established.

Assessment of risk factors for spinal cord ischaemia in surgery of thoracoabdominal aneurysms without use of adjuncts.

Between January 1983 and June 1986, 61 patients underwent resection of a thoracoabdominal aneurysm (TAA) by means of simple cross-clamping without the use of adjuncts. All patients survived the operation. Mortality was 6.5% at 30 days and 16.4% at 1 year. Spinal cord injury occurred in 8 patients. Three patients sustained paraplegia and 5 patients recovered from paraparesis within 6 months. In univariate analysis, risk factors were the presence of symptoms (P less than or equal to 0.01) and emergency operation (P less than or equal to 0.03). Spinal cross-clamptime (ACX), aetiology and the number of open intercostal arteries (ICA) did not appear to be single denominators for spinal cord injury. Testing clusters of variable related to spinal cord injury revealed an increased risk for the group of patients (n = 20) with type I (most of the thoracic and the upper abdominal aorta) and type III (the distal half of the thoracic and varying segments of the abdominal aorta) aneurysms, when the number of ICA was greater than or equal to 4 or less than or equal to 1, with a spinal ACX of greater than or equal to 35 min, and in the presence of symptoms and previous dissection (P = 0.001). In patients (n = 19) with type II aneurysm (involving most of the thoracic and most of the abdominal aorta) an increased risk was present when the number of open ICA was greater than or equal to 4, with a spinal ACX of greater than or equal to 35 min and in the presence of symptoms (P = 0.01). Spinal cord injury was confined to these types of TAA (P less than or equal to 0.001) and paraplegia occurred only in type I and III aneurysms.

Cerebral oxygenation during changes in vascular resistance and flow in patients on cardiopulmonary bypass - a physiological proof of concept study.

Despite a rise in blood pressure, cerebral oxygenation decreases following phenylephrine administration, and we hypothesised that phenylephrine reduces cerebral oxygenation by activating cerebral α1 receptors. We studied patients on cardiopulmonary bypass during constant flow. Phenylephrine raised mean arterial pressure (α1‐mediated) from mean (SD) 69 (8) mmHg to 79 (8) mmHg; p = 0.001, and vasopressin raised mean arterial pressure (V1 mediated) from 69 (8) mmHg to 83 (6) mmHg; p = 0.001. Both drugs elicited a comparable decrease in cerebral oxygenation from 61 (7)% to 60 (7)%; p = 0.023 and 61 (8)% to 59 (8)%; p = 0.022, respectively. This implies that after phenylephrine or vasopressin administration, cerebral oxygenation declines as a result of cerebral vasoconstriction, due to either both cerebral α1 and V1 receptors being equipotentially activated or to an intrinsic myogenic mechanism of cerebral vasculature in reaction to blood pressure elevation.